PanSystem - Well Test Analysis Software

Quick Links to Information Below

• PanSystem Overview
• Typical Applications for PanSystem
• Key Technical Features of PanSystem
• PanSystem Technology Overview

• PanSystem 3.3 Released

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• EPS Software Brochure
• EPS Products At-A-Glance

PanSystem Overview

PanSystem has been the industry’s leading well test analysis program for more than 20 years.

PanSystem is dedicated to well testing, a key technical function in the oil and gas industry. A pressure transient well test has the unique ability to obtain information from within the reservoir surrounding the well. With the appropriate testing techniques well testing can provide a wealth of information.

• Permeability of the near-wellbore region and the reservoir-at-large
• Vertical permeability, vertical communication in layered systems
• Completion efficiency, effective open interval size (over life of well)
• Well performance (over life of well)
• Reservoir structure (boundaries, heterogeneities)
• Nature of pressure support
• Connected pore volume and initial hydrocarbons in place
• Reservoir pressure
• Production forecasts

PanSystem provides many complementary tools for well test interpretation and analysis. This figure shows flow regimes, straight line diagnostics, and model responses (showing two sensitivities which can be seen on the plot and whose parameters are displayed in the tabbed results box bottom right).

Typical Applications for PanSystem

The task of designing, executing, and analyzing a well test depends on operating conditions, completion type, and reservoir type. PanSystem analyzes a wide range of assets and situations.

• Low Pressure Reservoirs, Heavy Oil: Wellbore fill-up and leak-off tests
• ESP Pumping Wells: Acoustically-derived pressures and rates
• Medium Oil Reservoirs: Conventional drawdown and build-up tests
• Gas Wells: Conventional analysis using real gas pseudo-pressure, turbulent skin analysis for high rate wells, and gas well deliverability by empirical (C-and-n) and LIT methods
• Volatile Oil/Condensate Reservoirs: Conventional analysis techniques, but using multiphase pseudo-pressure to model phase behavior and its effect on relative permeability (liquid dropout)
• Hydrothermal Wells: Steam
• Gas and Water Injection Wells: Injection and fall-off tests, including multi-region analysis
• Interference Tests: Interwell permeability and ΦCt from type-curve analysis and/or history matching by simulation
• Multi-Layered Reservoirs: Conventional analysis or specialized testing technique (MLT)
• Varying Rate Tests: Rates measured on surface or with downhole flowmeter
• Permanent Downhole (or Surface) Gauges: Special PDA section to analyze long-term pressure and rate records for hydrocarbons in place

From large scale reservoir characterization to the monitoring of individual well performance, the results of well test analysis provide information for many important operational decisions.

• Workover: Completion efficiency from skin factor and early time derivative shape, open interval length for stimulation or re-perforation
• Reservoir Characterization: Horizontal permeability (from kh), vertical permeability, boundaries and heterogeneities, gas cap/aquifer support, pressure support from second compartment for reservoir model refinement, and field development planning
• Reserves Estimation: Extended production test, long-term flowing pressure record (with permanent downhole gauge), build-up testing for reservoir model refinement, and field development planning
• Production Performance Prediction: Single well forward prediction with material balance included for field development planning
• Reservoir Pressure Decline for Field Development Planning

Key Technical Features of PanSystem

PanSystem’s graphical interface offers the user an efficient workflow. Its versatile data processing and analysis capabilities meet the challenges presented by the high performance of modern pressure gauges and the large volumes of data which they can acquire.

• Versatile Data Preparation
  • Easy entry of basic rock and fluid parameters
  • Import of raw data
    • ODBC databases supported (Weatherford RMS or any standard SQL)
    • Import from file or Microsoft Excel spreadsheet
    • More than adequate capacity (20 million data points)
    • Append new data to existing data
  • Data processing
    • Wavelet transform filter for outlier removal, de-noising, and reduction
    • Large choice of data reduction and smoothing algorithms
    • Data manipulation (function, shift, copy, paste, merge, resample, tidal filter)
  • Flowrates
    • Manual and automatic identification of rate change events
    • Flowrate averaging from long-term production records
    • Wavelet filter reduces size of rate data channel while honoring cumulative production
  • Wellhead to bottomhole flowing pressure conversion using VFP format flowing pressure files, EPS Products’ WellFlo application, or simplified dry gas model
• Analysis
  • Wide range of wellbore, reservoir, and boundary models
  • User-defined models can be easily integrated
  • Up to six different models can be investigated in a single file
  • Diagnostic plots include log-log with selection of pressure derivatives, rate normalization and superposition/convolution, line-fitting, and type-curve matching
  • Quick single-well simulation allows rapid validation of selected models and parameters
  • Auto-regression for automatic parameter optimization
  • Pressure decline analysis (PDA) facility for the analysis of long term flowing pressure and rate (or cumulative) data to estimate hydrocarbons in place using:
    • Agarwal-Gardner type-curves
    • Equivalent constant rate (ECR) deconvolution method
• Simulation
  • In addition to the quick simulation for model validation, PanSystem contains multi-well, multi-layer simulators to generate pressure from flowrate (advanced simulation) and, less conventionally, flowrate from pressure
  • PanSystem’s companion numerical well test simulator, PanMesh, available under a separate license, provides more complex well and reservoir configurations which are beyond the capabilities of analytical models
• Deliverability and Production Forecasting
  • From WTA, or from direct measurements of flowing pressures and rates
    • Conventional IPR for oil or water
    • Empirical C-and-n and rigorous LIT methods for gas wells
  • Production forecasting module predicts flow profile through transient, semi-transient, and semi-steady state phases
    • Constant bhfp option or constant thfp (using a VFP format file for tubing performance)
    • Reservoir pressure computed in depletion cases
• Design
  • Well test design module includes test time and flowrate advisor
  • Predicted pressure response generated by advanced simulation includes gauge resolution, noise, and drift
• PanManager
  • Opens multiple PanSystem files for comparison of gauge datasets and interpretations
    • Well tests run in same well at different times
    • Well tests run in different wells
    • Different interpretations of one well test
• Reporting
  • User-configurable report format can be stored as a template
  • Output to printer or to Microsoft Word
  • Version 4 of the regulatory Pressure ASCII Standard (PAS) format of the Alberta EUB supported for TRG.PAS
• PanScan
  • Utility to scan in mechanical gauge records and digitize these ready for import into PanSystem

PanSystem Technology Overview

PanSystem is the most widely recognized software from eP's EPS product line. It has been used for well test interpretation by many engineers around the world since its original launch in 1985. Originally written for DOS as the first PC's became available to engineers in the oil industry, the product has been continuously updated to meet the increasingly demanding standards in IT and Petroleum Engineering. The software is now available on Windows NT, 95, 98, 2000 and XP. It will operate across networks and is compatible with ASP Web technology.

Most of the major international and many national oil and gas companies have standardized on PanSystem as it combines the most advanced technology with a high degree of usability, serving the needs of both beginners and experts. This combination makes PanSystem the most attractive tool for well test analysis on the market.

Recently the drive to extend well test analysis to more accurately reflect reservoir geology has prompted eP to develop and release a sister product, PanMesh. PanMesh integrated with PanSystem and greatly extending the functionality of the product to allow the accurate modeling of different geological structures. (Check the PanMesh section for more details).

PanSystem is also available in Russian and Chinese so that engineers in these important oil provinces also have access to the best available technology in well testing.

Well testing is a key technical function within the oil and gas industry. The results of the analysis of data from well tests are used to make multi-million dollar investment decisions. Often a well test is used as the principle technology to monitor the performance of such investments or to diagnose unexpected well or reservoir behavior.

PanSystem is the leading well test analysis program in the industry. It is used as a corporate standard by most multinational companies and many national oil companies. This document describes the technology used in PanSystem and how it is applied to well test analysis.

Objectives of PanSystem

The objective of PanSystem is to provide a system to enable the user to perform efficiently all tasks associated with the design, analysis and simulation of well test data.

This process can be described by the flow diagram below:

Well Test Analysis WorkFlow

The flow diagram above focuses on well test analysis as this is the primary application of PanSystem. Well test design is an important function also addressed by PanSystem and several key features of the application focus on this important task.

Well Test Design Workflow

PanSystem enables the processes of Design and Analysis to be performed efficiently and accurately to ensure that the well test data recorded meets the objectives set for the test.

The rest of this document will review the technology in each of the areas described above to clarify how PanSystem delivers this functionality.

Data Handling

Data handling is one of the key strengths of PanSystem. In many ways the key technical capability of well test analysis software is the ability to handle very large data files, while presenting the data on screen to be manipulated interactively.

The data required by PanSystem for analysis is of different types. Firstly the static data required for the analysis. These data types are:

• Well Parameters
• Layer Parameters
• Fluid Parameters

The screen shot below shows the data entry screens for Fluid parameters. The essential data (without which an analysis is not possible) are identified by the red fields.

PanSystem Static Data Entry

PanSystem includes correlations to estimate parameters where field data is not sufficient.

Further assistance and advice is provided by a Wizard system. Wizards provide help screens on a step by step basis as the user works through a task with the software. See section on User support for more details.

Data Import and Export

The most powerful aspect of data entry in PanSystem is the capability to load large ASCII files as are typically generated by modern electronic pressure gauges (the second data type required for analysis).

There is no limit to the file size that PanSystem can import and it is easy to repeatedly import data from a number of gauges from the same well test in order to compare and quality control the data.

A template can be defined to allow the user to import files which are of the same format.

Once data has been imported to PanSystem, a number of tools are available to enable the user to smooth and filter the data. Some well tests are affected by tides and PanSystem supports tide table import to correctly filter these effects out of the reservoir signal.

All of the functionality in this area of PanSystem is designed to speed the process of data import and plotting to get the user to the point of being able to start an analysis as quickly as possible from whatever source the data originated.

Data export is also easy to achieve for large ASCII files. It may be that the data once prepared needs to be shared with another organization which does not have access to PanSystem and in this case the data may be exported to a columnar ASCII file (which may be comma space or tab separated).

It is often the objective to compile a written report combining graphics and text in ways specific to the needs of a particular company. PanSystem allows Copy and Paste functionality as well as its internal reporting facilities. Graphics may be captured and compressed and exported in a range of graphic file formats including GIF, BMP, JPG and TIF.

The Canadian EUB electronic reporting system is a supported format allowing electronic filing of well tests performed in Canada as required by regulation.

Reporting

Reporting is catered for through the ability to generate detailed reports in PanSystem which mix text and graphics and are arranged in sections allowing the user to build a template of the report for consistency. These reports allow detailed annotation of all the plots generated by PanSystem and as all the interpretation parameters are stored in a PanSystem file along with the data, it is very easy to regenerate a report from the original data if required.

If necessary, the report may be output to Microsoft Word for further formatting or editing.

Altogether the data handling capabilities in PanSystem enable it to operate effectively in importing, plotting, reformatting, comparing, smoothing, filtering and quality controlling data. These functions include the ability to import data from different sources and export and report data to different formats as required. The flexibility and ease of use of this area of PanSystem is recognized as one of its major strengths.

Analysis

The process of well test analysis has evolved over the years and oil company engineers have developed various techniques from the experience they have had in the wells they have tested. PanSystem captures the best of these techniques to allow a range of approaches to be taken when analyzing pressure transient data.

The most widely accepted starting point for well test analysis is the log-log derivative plot. An example is shown below.

PanSystem The Log – Log Plot

This plot is set up by functioning the pressure and time appropriately so that the plot removes the effects of the specific rate history of the test whereby (in most circumstances) build up and draw down responses may be compared on the same basis with the same reservoir characteristics being reflected in the same shape of derivative plot. This allows engineers to compare the pressure response with a library of typical reservoir derivative shapes to identify the appropriate model with which to analyze the data.

Model Selection

This is the most crucial stage of the process as errors made here will translate directly into errors (often very large) in the reservoir parameters estimated by the analysis process.

Assistance is again provided through PanWizards in selecting the appropriate reservoir model and once the model is selected the user may progress to the process of reservoir parameter estimation.

Parameter Estimation

The user may chose to use the line fitting options on the log log plot, or the specialized plots (these are needed to arrive at an estimate of local reservoir pressure). Type curve matching may also be used to perform the parameter estimation – a technique which is often useful if there is incomplete data to be analyzed.

When the models have been selected and the parameters estimated the user will then have defined the model and estimated the parameters for each of the wellbore, reservoir and outer boundaries models.

Wellbore Models

• Constant Wellbore Storage
• Fair Wellbore Storage
• Hegeman Wellbore Storage
• Time Stepped Wellbore Storage

Reservoir Models

• Radial Homogeneous
• Vertical Fracture – Infinite Conductivity
• Vertical Fracture – Uniform Flux
• Vertical Fracture – Finite Conductivity
• Vertical Fracture – Limited Height
• Dual Porosity (Pseudo Steady State)
• Dual Porosity (Transient)
• Gas Cap / Aquifer Support
• General Intersecting Fault Model
• Three Layer Homogeneous with Cross Flow
• 2 Zone Composite
• 3 Zone Composite
• 4 Zone Composite
• Pinch Out (Bounded Model)
• Partially Sealing Fault / Linear Composite Model
• Slanted Well

Outer Boundary Models

• Infinitely Acting
• Single Fault
• Parallel Faults
• Intersecting Faults (30)
• Intersecting Faults (45)
• Intersecting Faults (60)
• Intersecting Faults (90)
• Intersecting Faults (120)
• U Shaped Faults
• Closed System
• 2-cell Compartmentalized
• Hexagonal Boundary

This extensive range of models and the ability to mix any combination of these allows for the analysis of all but the most complex geometries.

For all of these cases the model in question is a solution to the diffusively equation derived using analytical techniques. With the development of fast numeric solvers capable of calculating the pressure transient response throughout a generalized model of numerical elements that can be defined to honor any geometry, the impetus to develop new analytical models is fading.

PanSystem provides all of the standard and advanced approaches required to interpret well tests from all well test types. This functionality is at the heart of the application and has evolved with input from leading exponents of well testing into the most complete toolset for analysis of well tests available.

Simulation

On completion of the parameter estimation process the user has a separate model which should be valid for each of the early, middle and late time regions of the test. Simulation allows these models to be brought together to confirm that the total response generated by superposition of these models will match the observed transient data. The simulation may go further and allow the simulation of a complete test sequence of flowing periods verifying the consistency of the interpretation across all of the measured data.

It is often at this stage, during simulation, that data features such as depletion will be observed when no boundaries have been seen in the pressure transients, highlighting the value of integrating the interpretation performed on individual flow periods with the overall interpretation.

Quick Match

Quick Match as the name implies allow the user access to a very rapid simulation of the data which can be used to generate an initial simulation to observe how closeness of the match between the model and the real data. Often this is very close and a simple adjustment of the reservoir parameters will finalize the match.

PanSystem Quick Match

Another benefit of this feature is that it is a very powerful training tool. The user can very quickly learn the impact of changes model parameters have and their affect on the pressure simulation. This often lends useful insights as to how sensitive the resulting interpretation is to variations in the input data and helps to highlight the way that some model parameters interact.

The user can view the complete simulation of the test period in all of the specialized plots simultaneously to ensure the consistency of the interpretation.

Simulated and Measured Data Presented on all the Specialized Plots

Automatch

A complementary approach to the Quick Match simulation above is the Automatch feature. This enables the user to select points from the measured data set and have PanSystem regress the parameter estimates until a match is achieved with the simulation. This approach is recommended as a fine-tuning of a simulation rather than being recommended as an alternative to an engineered answer.

Advanced Simulation

Advanced Simulation extends the analytical simulation capabilities of PanSystem even further. With advanced simulation it is possible to set up a multi-well, multi layer system and calculate the pressure response at any point selected in the reservoir. This enables interference and pulse tests to be simulated as well as the analysis of multi layered well tests.

PanMesh

PanMesh is an advanced finite element based numerical simulator and is not supplied as part of the standard PanSystem package. PanMesh takes the process of simulation further allowing almost any geometry of well and reservoir to be simulated. PanMesh also includes powerful visualization, enabling the user to see how the pressure transient is affected by changes in the model geometry as the transient moves through the reservoir.

The sophistication of PanMesh enables the integration of the disciplines of well testing and geology by providing a tool to allow these disciplines to communicate in terms with which both are familiar.

This powerful simulation tool completes the functionality required to address any well test likely to be encountered in the oil and gas industry.

Production Prediction

Having analyses all of the data and derived a consistent interpretation, PanSystem can provide the user with an estimate of how the well will produce in the future through the production forecasting option. PanSystem is not designed to replace reservoir simulators in production planning and simulation. However, in many wells, hydraulically fractured low permeability wells and horizontal wells in low permeability for example, the transient period can be very long and this extra flush production can have an important impact on economics.

PanSystem Production Forecasting Plot

User Support

PanSystem provides the most sophisticated technology for well test design and analysis. Other packages can also make this claim, however, PanSystem is second to none in backing up its leading technology with the most effective user support. This is the key to unlocking the power of the technology and without it PanSystem would not have achieved the wide success it has.

Support Service

eP has some of the world’s leading experts in well testing technology. The company prides itself in its ability to design and analyze the most complex of well tests. Perhaps as important, eP's experts know when data is un-interpretable or a design will not work. This expertise is available on a consultancy basis and also, to a limited extent through, software maintenance contracts to support PanSystem users in their application of the software.

PanWizards

A range of PanWizards are provided within the software which will take the user through particular processes, providing guidance on the use of the software and on the petroleum engineering aspects of a problem.

What Next? Will evaluate where a user is in the workflow process and indicate which steps remain to be completed. The wizard will then step the user through these processes to ensure they are completed successfully.

Reservoir Description is a wizard to assist in data entry, highlighting the important parameters that must be completed and their meaning before the user can progress to the analysis section.

Enter Gauge Data deals with the specific problems occasionally encountered when importing data of an unfamiliar format.

Rate Changes provides support to the user to enter the correct rate history which corresponds to the pressure data to be analyzed.

Reduce Data Points assists in the data reduction process which is often helpful in dealing with the very large data sets that can be generated by modern electronic pressure gauges.

Model Selection provides advice to the user on which model is most appropriate for the well test being analyses Suggestions are made as to which issues should be considered in selecting an appropriate model.

Validation guides the user through the various simulation tools in PanSystem.

Test Design is a sophisticated tool which should always be used to guide users in well test design. This process ensures that the well test will be appropriately designed to meet its objectives and that , for example, will be capable of flowing at the design rates. Other important issues such as ensuring that the resolution of the gauge will be high enough to measure the response anticipated are considered.

Reports help to generate the required output from the program.

PanWizards are powerful tools to aid with engineering as well as the software features in the well test design and analysis work flows.

Units Systems

PanSystem is used in almost every known oil province and with the industry’s infamous approach to measurement units, it has had to be equipped with a very sophisticated units conversion and support system. Internally PanSystem operates in oilfield units but a wide range of SI units are provided through the user interface and the user can configure these or oilfield units to create hybrid unit systems to support those in use in their particular application.

Documentation

Extensive online documentation is available with PanSystem. In the latest version, the manual can be accessed from the Help menu. A printer ready version accompanies the software on CD and can be printed off freely by licensed users.

PanManager

Increasingly, well testing, the procedures, software and data associated with tests are being regarded and managed as an enterprise asset. As cost reduction pressures and new technologies such as the internet develop, there is a clear shift in emphasis appearing in requests from the eP PanSystem client base.

Increasingly usability and data access across an organization are highlighted as being more important than new technical analysis features. This is probably underlined by the fact that PanSystem (and other well testing software) is now quite mature in terms of its technical capabilities and the general solver capabilities of finite element simulators means that there is little more room for development in the area of analytical models.

PanManager is the product initiative which will address these needs.

PanManager is a software feature which allows the user to open multiple PanSystem files and compare one test with another on the same well or one well with another.

This approach to supporting the user continues to deliver the maximum productivity and cost efficiency. The Knowledge Base approach increasingly taken by oil companies captures an organization’s experiences with their field data and will increase asset value by reducing risk from a purchaser’s perspective when such assets are being sold.

Conclusion

PanSystem was originally developed to help engineers analyze well tests in an era when the only technology other than a pen and paper available to them was a corporate mainframe on another continent. The development of much more sophisticated well technology and IT developments as well as the changing needs of the industry have driven the development of PanSystem into a much more powerful analytical tool and support system for well testing.

PanSystem is still the best tool on the market to help engineers design and analyze well tests. eP continues to invest in this technology and will ensure by doing so that PanSystem retains its position as a leader in well testing software.

PanSystem 3.3 Released

Data Preparation

• Data import into PanSystem via data prep has been expanded to include:
  • Standard ODBC and RMS (Weatherford permanent gauge data system) data import.
  • MS Excel file import.
  • Clipboard copy and paste.
• New Date and Time format support
  • Numerous defects of date/time combinations have been resolved
• Hi Speed, multi-million point data import
• On import – improved detection of invalid data patterns
• Data handling for large data sets comprising millions of points.
• Statistical outlier removal filter.
• Data reduction using wavelet filtering on pressure and rate data.
• Canadian EUB 4.0 data import / export.
• Export the rate flow and volume from DataPrep - rate changes with headers.
• Find feature added to DataPrep.
• Ability to accommodate 10,000 rows of rate data in rate change table.
• Progress bar now used extensively in product.
• Indication of warning messages in Import Dialog window.

Analysis

• New (control-right mouse-click) method of selecting all flow periods except the last on the data edit, test overview, and PDA plots.
• Pressure Decline analysis functionality now includes finite conductivity fracture model Type curves.
• Type-curve labeling
• Type-curve filtering
• Group all flow periods with a single click
• Enhanced capability for displaying and hiding the Quick Match results box and data traces
• Plot axis scaling logic has been improved to produce better-looking plots

General

• Delete key does the same as the delete toolbar button.
• Open file dialog used last folder for all types of files.
• Mouse interface lacked deletions for line plots, single RT shift now deletes.
• Calculate rock pore volume compressibility from Young’s Modulus and Poisson’s ratio on the oil fluid parameters sub-dialog, the gas fluid parameters sub-dialog, and the condensate fluid parameters sub-dialog.

PanMesh Numerical Modeling

• A completely revised graphical interface for PanMesh, with a range of new positioning and diagnostic tools, including:
  • Clipping plane adjustment tools on the PanMesh toolbar.
  • Axis/triad (X, Y, Z) tool displayed within the perspective view to assist users with orientation.
  • View centering facility to center the reservoir image for zooming, panning and rotating.
  • Series of stock views for the reservoir image, including:
    • Completion view (zoom-in to the completion zone/s).
    • Flow plane view (zoom-in to flow plane).
    • Plan view of iso surface (surface of equal pressure).
    • Elevation of selected point (zoom-in to selected point).
    • View flow into completions (view flow plane/arrows at selected completion zone).
  • View management facility for saving, editing and naming "snapshots" of the reservoir image in the perspective view.
  • Data view controls for the cut plane, flow plane and stream tube.
  • Axial adjustment tools for the cut plane and flow plane.
  • Flow analysis facility in the edit mesh dialog, which can be used in conjunction with the view flow into completions facility.
  • Simulation time estimation displayed in the status bar.